On Fri, Feb 22, 2019 at 04:28:35PM +0200, Tzvetomir Stoyanov wrote:
> In order to match host and guest events, a mapping between guest VCPU
> and the host task, running this VCPU is needed. Extended existing
> struct guest to hold such mapping and added logic in read_qemu_guests()
> function to initialize it. Implemented a new internal API,
> get_guest_vcpu_pids(), to retrieve VCPU-task mapping for given VM.
>
> Signed-off-by: Tzvetomir Stoyanov <tstoyanov@xxxxxxxxxx>
> ---
> tracecmd/include/trace-local.h | 3 ++
> tracecmd/trace-record.c | 57 +++++++++++++++++++++++++++++++++-
> 2 files changed, 59 insertions(+), 1 deletion(-)
>
> diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
> index d7bdb1f..ef6848f 100644
> --- a/tracecmd/include/trace-local.h
> +++ b/tracecmd/include/trace-local.h
> @@ -236,6 +236,9 @@ void show_instance_file(struct buffer_instance *instance, const char *name);
>
> int count_cpus(void);
>
> +#define VCPUS_MAX 256
Is VCPUS_MAX intended to be used somewhere outside of trace-record.c? If not, I
think we should keep it there locally and not expose it.
> +int *get_guest_vcpu_pids(int cid);
> +
> /* No longer in event-utils.h */
> void __noreturn die(const char *fmt, ...); /* Can be overriden */
> void *malloc_or_die(unsigned int size); /* Can be overridden */
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index c57ed6b..59f0197 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -2752,6 +2752,7 @@ struct guest {
> char *name;
> int cid;
> int pid;
> + int cpu_pid[VCPUS_MAX];
> };
>
> static struct guest *guests;
> @@ -2772,9 +2773,10 @@ static char *get_qemu_guest_name(char *arg)
> static void read_qemu_guests(void)
> {
> static bool initialized;
> + struct dirent *entry_t;
> struct dirent *entry;
> char path[PATH_MAX];
> - DIR *dir;
> + DIR *dir, *dir_t;
>
> if (initialized)
> return;
> @@ -2830,6 +2832,49 @@ static void read_qemu_guests(void)
> if (!is_qemu)
> goto next;
>
I think the following section should go into separate function since this one is
already getting too long. Then here we can just do:
read_qemu_guest_vcpus(&guest);
Where read_qemu_guest_vcpus can be something like that:
static void read_qemu_guest_vcpus(struct guest *guest)
{
struct dirent *entry;
char path[PATH_MAX];
size_t buf_len = 0;
char *buf = NULL;
int vcpu;
DIR *dir;
FILE *f;
snprintf(path, sizeof(path), "/proc/%d/task", guest->pid);
dir = opendir(path);
if (!dir)
return;
for (entry = readdir(dir); entry; entry = readdir(dir)) {
if (!(entry->d_type == DT_DIR && is_digits(entry->d_name)))
continue;
snprintf(path, sizeof(path), "/proc/%d/task/%s/comm",
guest->pid, entry->d_name);
f = fopen(path, "r");
if (!f)
continue;
if (getline(&buf, &buf_len, f) < 0)
goto next;
if (strncmp(buf, "CPU ", 4) != 0)
goto next;
vcpu = atoi(buf + 4);
if (!(vcpu >= 0 && vcpu < VCPUS_MAX))
goto next;
guest->cpu_pid[vcpu] = atoi(entry->d_name);
next:
fclose(f);
}
free(buf);
}
Thank you,
-- Slavi
> + snprintf(path, sizeof(path), "/proc/%s/task", entry->d_name);
> + dir_t = opendir(path);
> + if (dir_t) {
> + unsigned int vcpu;
> + char *buf = NULL;
> + char *cpu_str;
> + FILE *ft;
> + size_t n;
> + int j;
> +
> + for (entry_t = readdir(dir_t); entry_t; entry_t = readdir(dir_t)) {
> + if (!(entry_t->d_type == DT_DIR &&
> + is_digits(entry_t->d_name)))
> + continue;
> + snprintf(path, sizeof(path),
> + "/proc/%s/task/%s/comm",
> + entry->d_name, entry_t->d_name);
> + ft = fopen(path, "r");
> + if (!ft)
> + continue;
> + getline(&buf, &n, ft);
> + if (buf && strncmp(buf, "CPU ", 4) == 0) {
> + cpu_str = buf;
> + while (*cpu_str != '\0' &&
> + isdigit(*cpu_str) == 0)
> + cpu_str++;
> + if (*cpu_str != '\0') {
> + j = 0;
> + while (cpu_str[j] != '\0' &&
> + isdigit(cpu_str[j]) != 0)
> + j++;
> + cpu_str[j] = '\0';
> + vcpu = atoi(cpu_str);
> + if (vcpu < VCPUS_MAX)
> + guest.cpu_pid[vcpu] = atoi(entry_t->d_name);
> + }
> + }
> + free(buf);
> + fclose(ft);
> + buf = NULL;
> + }
> + }
> +
> guests = realloc(guests, (guests_len + 1) * sizeof(*guests));
> if (!guests)
> die("Can not allocate guest buffer");
> @@ -2875,6 +2920,16 @@ static char *parse_guest_name(char *guest, int *cid, int *port)
> return guest;
> }
>
> +int *get_guest_vcpu_pids(int cid)
> +{
> + int i;
> +
> + for (i = 0; i < guests_len; i++)
> + if (cid == guests[i].cid)
> + return guests[i].cpu_pid;
> + return NULL;
> +}
> +
> static void set_prio(int prio)
> {
> struct sched_param sp;
> --
> 2.20.1
>
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